Rock drill

ABSTRACT

Means for directing flushing fluid into a rock drill at a point intermediate the ends of the striking bar.

United States Patent Bailey et al. 1 July 8, 1975 [54] ROCK DRILL 2,056,293 10/1936 Rasch 173/80 2,125,133 71938 T 173 80 Inventors: Edward A. Bailey, Newport; LOlliS a]. H u LeBlanc, Claremom both of 3,589,352 6/1971 Carlsson 173/80 N.H. 3,701,386 10/1972 Feucht 173/80 [73] Assignee: Joy Manufacturing Company,

Pittsburgh, Pa. Filed: Jan. 1974 Primary Examiner-James A. Lepplnk [21] Appl. No.: 437,913

[52] U.S. Cl H 173/80; 173/80 57 ABSTRACT [51] Int. Cl. B25111 9/00 [58] Field of Search 173/80 Means for directing flushing fluid Into a rock dl'lll at a [56] References Cited point intermediate the ends of the striking bar.

UNITED STATES PATENTS 904,692 11/1908 Greve et a1. 173/80 5 Claims, 2 Drawing Figures ROCK DRILL It is well known in the art of percussive tools such as rock drills to provide flushing fluid to the rock face axially through the drill steel and drill bit for the purpose of flushing rock dust and chips out of the hole being drilled and to dissipate the heat generated by the drilling operation. ln the prior art flushing fluid such as air or water has typically been introduced into the drill steel through communicating coaxial passages in the striking bar, hammer piston and backhead of the drill. However, this method for introducing flushing fluid has proven to be impractical and undesirable in some drill designs, notably in hydraulic drills, for a variety of reasons. For example, in a hydraulic drill the hammer piston typically is quite elongated and slender relative to the hammer piston of a comparably sized pneumatic drill. An axial bore for fluid flow through a hammer piston of such slender proportion would unduly limit the maximum attainable piston cross section area and mass for any given piston dimensions or material specification, thereby unduly limiting optimal piston strength characteristics and energy transfer efficiency. Therefore, in a hydraulic drill a solid piston is generally preferable to a piston of comparable external dimensions but including an axial bore for fluid flow. By way of further example, known hydraulic drill designs often include a gas charged energy absorbing accumulator which communicates with the rearwardmost end of the hammer piston for well known purposes such as the conservation of piston upstroke energy. Many drill designs specify such an accumulator to be located within the drill housing axially intermediate the drill backhead and the hammer piston. The utilization of such a design wherein flushing fluid is introduced axially via the drill backhead and hammer piston would precipitate unnecessary design complications such as special sealing arrangements between the accumulator and the flushing fluid passageways.

These and other complications of prior art drill design are overcome by the present invention which includes means whereby flushing fluid may be introduced directly into the striking bar from the front of the drill housing thereby eliminating the need for an axial through bore in the hammer piston.

Additional objects and advantages of the invention herein are fully explained in the following desription and illustrations in which:

FIG. 1 is a longitudinal central section of a fragmentary forward portion of a rock drill constructed in accordance with the principles of the present invention; and

FIG. 2 is a transverse section of a striking bar and chuck driving gear assembly taken on line 22 of FIG. 1.

FIG. 1 illustrates the forward end portion of a rock drill generally designated at 10. Rock drill comprises a rigid generally annular housing 12 having disposed generally coaxially therewithin in a manner to be more fully detailed hereinbelow an elongated cylindrical striking bar 30. A forward end portion 3] of striking bar 30 which extends forwardly of the drill housing 12 has releasably coupled to the forwardmost end thereof one end of a forwardly extending drill steel 18 by well known means such as an annular coupling collar 80 which engages rope threads 82 on the adjacent ends of striking bar 30 and drill steel 18. The drill steel 18 has rigidly affixed upon its forwardmost end a well known drill bit 19.

The rearwardmost end (not shown) of the striking bar 30 is engagable by well known cyclic impacting means such as a hydraulically reciprocable hammer piston (not shown) disposed within the housing 12 for the purpose of delivering repetitive percussive blows to the striking bar 30 and thereby producing a percussive drilling action upon a rock face 20 located forwardly adjacent the bit 19. Inasmuch as such cyclic impacting means are well known to those versed in the art and inasmuch as detailed description thereof is in any case not necessary for a complete disclosure of the present invention, such detailed description is not included herein. Applicant hereby refers to U.S. Pat. No. 3,470,970 for a detailed description of one such cyclic impacting means.

A generally annular forward drill head 22 is rigidly affixed to the forwardmost end of housing 12 by any suitable means as for example by a plurality of bolts 24.

A generally annular chuck driving gear 14 disposed within the housing 12 receives coaxially therewithin the striking bar 30 in a rotatable driving relationship. The gear 14 is captively retained within housing 12 in coaxial rotatable relationship therewith by suitable means such as forward and rearward thrust bearings 16 and 17, respectively, interposed between rotating and nonrotating elements.

The striking bar 30 comprises a plurality of circumferentially spaced external splines 44 disposed intermediate the axial ends thereof, which splines 44 are drivingly engaged by a respective plurality of mating splines 46 spaced circumferentially about the internal periphery of an annular chuck driver member 48. In similar fashion a plurality of splines 50 circumferentially spaced about the external periphery of driver 48 are drivingly engaged by a respective plurality of mating splines 52 disposed about the radially outwardly adjacent internal periphery of gear 14 whereby striking bar 30 is maintained in rotatable driving relationship with gear 14. Typically the gear 14 is driven in rotation by suitable well known means (not shown) to impart axial rotation to the striking bar 30 during drill operation. Applicant hereby refers to the hereinabove cited U.S. Pat. No. 3,470,970 for a description of one such rotational driving means.

An annular bushing member 54 is disposed within the gear l4 radially intermediate a rearward inner peripheral portion thereof and a portion of striking bar 30 rearwardly adjacent splines 44 to provide radial support for the rearward portion of striking bar 30. An annular forward bushing member 38 is sealingly disposed within head 22 radially intermediate a forward inner peripheral portion 26 thereof and striking bar portion 3| to provide radial support for striking bar forward portion 31. The bushing 38 is rigidly sealingly retained within portion 26 of head 22 longitudinally intermediate an annular shoulder 32 which defines the rearward terminus of periphery portion 26 and a radially inwardly extending flange 39 of an annular collar 40, which collar 40 releasably rigidly engages the forwardmost outer peripheral end of head 22 by any suitable means, for example mating threads 42.

The present invention resides in an arrangement whereby flushing fluid such as air or water is introduced into the striking bar 30 intermediate the axial ends thereof by means comprising a port 58 which extends longitudinally through the bushing 38 to commu' nicate between the forward exterior of drill l and an interior chamber 70. Chamber 70 is substantially defined by radially adjacent peripheral portions of gear 14 and striking bar 30 and by annular seals 68, 66 and 64. The annular seal 64 is shown as being sealingly disposed rearwardly adjacent bushing 54 intermediate radially adjacent peripheral portions of striking bar 30 and gear 14. The forward annular seal 66 is sealingly disposed intermediate radially adjacent peripheral portions of striking bar portion 31 and bushing 38. The annular seal 68 is sealingly disposed radially intermediate at inner peripheral portion 34 of head 22 extending rearwardly of shoulder 32, and the radially inwardly adjacent periphery of gear l4.

Port 58 is adapted at its forwardmost end by suitable means, such as threads 60, to couple a hose 62 which delivers a flushing fluid to the drill from any suitable source (not shown). The fluid so provided circulates within chamber 70 but is precluded by the sealing arrangements defined hereinabove from reaching bearings 16 and 17, the hammer piston (not shown) and all other drill rotating and impacting elements.

The fluid supplied to chamber 70 flows into striking bar 30 via a plurality of circumferentially spaced transverse bores 72 extending radially therein to provide communication between the chamber 70 and a forwardly open axial bore 74, the rearward terminus of which is located forwardly of the rearward end of bar 30. The bores 72 are preferably spaced apart longitudinally within the longitudinal extent of the roots of splines 44 inasmuch as this location takes advantage of the maximum section modulus of the bar 30 thereby providing maximum support for the stress concentrations which occur during drill operation.

The bore 74 communicates through an axially aligned bore 76 in drill steel I8 with suitable passageway means 78 in bit 19 whereby flushing fluid from a suitable source (not shown) enters the drill via port 58, circulates through the space 70 defined hereinabove, thence passes through bores 72 and into bore 74, thence through bore 76 and finally through passageway means 78 into the base of the hole being drilled thus flushing dust and other matter therefrom.

Inasmuch as the invention herein primarily resides in an arrangement wherein flushing fluid is introduced to the striking bar intermediate the axial ends thereof, various modifications to the preferred embodiment discussed hereinabove can be made without departing from the scope of the invention, for example; the inven tion is equally applicable to a pneumatic drill or other percussive tool requiring flushing fluid, and may be applied to such tools with or without rotational apparatus such as the gear 14 and bearings l6 and I7; additional seals adjacent seals 64, 66 and 68 may be utilized to enhance sealing characteristics; the configuration and placement of seals may be altered as conditions dictate; a controlled leakage past seal 66 over striking bar for the purpose of cooling the bearing area within bushing 38 may be provided; a single radial bore or other passageway means in striking bar 30 in lieu of bores 72 are contemplated; bores 72 may be located either rearward or forward of the splines 44; and the like These and other alternative embodiments having been envisioned and anticipated it is respectfully requested that the invention herein be interpreted broadly and limited only by the scope of the claims appended hereto.

What is claimed is:

1. In an elongated percussively actuated rock drill wherein a piston member repetitively engages an elongated striking bar within a body member, the improvement comprising: a chamber defined intermediate said striking bar and said body member; sealing means cooperable with said body member and said striking bar to restrict flow from said chamber; said striking bar including forward and rear bearing portions and a splined driver portion located axially intermediate said bearing portion; first longitudinally extending forwardly open passageway means in said striking bar having the rearward end thereof terminating intermediate the axial ends of said striking bar; second passageway means in said striking bar and communicating between said first passageway means and said chamber; said second passageway means including at least one transversely ex tending bore having the outer end thereof in communication with said chamber adjacent a root surface of a respective one of the splines of said driver portion; and third passageway means having one end thereof communicating with said chamber and having the other end thereof adapted to communicate with a fluid flow source.

2. A rock drill assembly as specified in claim 1 wherein at least a major portion of said first passageway means is coaxial with respect to the longitudinal axis of said striking bar.

3. A rock drill assembly as specified in claim 1 wherein said other passageway means is adapted to communicate with a fluid flow source adjacent the forward end of said body member.

4. In a striking bar having forward and rear bearing portions and a splined driver portion located axially intermediate said bearing portions and being adapted to be received within an elongated rock drill assembly wherein a piston member repetitively engages such a striking bar, the improvement comprising: first longitudinally extending forwardly open passageway means in said striking bar having the rearward end thereof terminating intermediate the axial ends of said striking bar; second passageway means in said striking bar and communicating between said first passageway means and the exterior of said striking bar; and said second passageway means including at least one transversely extending bore having the outer end thereof in communication with the exterior of said striking bar adjacent a root surface of a respective one of the splines of said driver portion.

5. A striking bar as specified in claim 4 wherein at least a major portion of said first passageway means is coaxial with respect to the longitudinal axis of such a striking bar. 

1. In an elongated percussively actuated rock drill wherein a piston member repetitively engages an elongated striking bar within a body member, the improvement comprising: a chamber defined intermediate said striking bar and said body member; sealing means cooperable with said body member and said striking bar to restrict flow from said chamber; said striking bar including forward and rear bearing portions and a splined driver portion located axially intermediate said bearing portion; first longitudinally extending forwardly open passageway means in said striking bar having the rearward end thereof terminating intermediate the axial ends of said striking bar; second passageway means in said striking bar and communicating between said first passageway means and said chamber; said second passageway means including at least one transversely extending bore having the outer end thereof in communication with said chamber adjacent a root surface of a respective one of the splineS of said driver portion; and third passageway means having one end thereof communicating with said chamber and having the other end thereof adapted to communicate with a fluid flow source.
 2. A rock drill assembly as specified in claim 1 wherein at least a major portion of said first passageway means is coaxial with respect to the longitudinal axis of said striking bar.
 3. A rock drill assembly as specified in claim 1 wherein said other passageway means is adapted to communicate with a fluid flow source adjacent the forward end of said body member.
 4. In a striking bar having forward and rear bearing portions and a splined driver portion located axially intermediate said bearing portions and being adapted to be received within an elongated rock drill assembly wherein a piston member repetitively engages such a striking bar, the improvement comprising: first longitudinally extending forwardly open passageway means in said striking bar having the rearward end thereof terminating intermediate the axial ends of said striking bar; second passageway means in said striking bar and communicating between said first passageway means and the exterior of said striking bar; and said second passageway means including at least one transversely extending bore having the outer end thereof in communication with the exterior of said striking bar adjacent a root surface of a respective one of the splines of said driver portion.
 5. A striking bar as specified in claim 4 wherein at least a major portion of said first passageway means is coaxial with respect to the longitudinal axis of such a striking bar. 